NH3 effect on the growth of carbon nanotubes on glass substrate in plasma enhanced chemical vapor deposition

The effects of NH3 on the growth characteristics of carbon nanotubes (CNTs) were systematically investigated in plasma enhanced chemical vapor deposition (PECVD) with C2H2 as a carbon source. CNTs were not formed when N-2 was used instead of NH3. Carbon films instead of CNTs were observed without NH3. As the growth of CNTs with only C2H2 proceeded after the initial growth of CNTs with NH3 and C2H2, films were formed with rugged surface morphology instead of nanotube-features. High-resolution transmission electron microscopy revealed that carbon films consisted of graphite carbons, and 20-30 nm graphite onions covered with amorphous layers. NH3 was found to be essential to the growth of CNTs in the PECVD system. NH3 may provide additional etching effects for the growing carbon surface. and suppression of carbon supply. (C) 2002 Elsevier Science B.V. All rights reserved.